Variable capacity rotary pump



Aug. 12, 1952 Filed Jan. 11, 1946 7 Sheets-Sheet 1 12, 1952 A. M. SHAW 2,606,503

VARIABLE CAPACITY ROTARY PUMP Filed Jan. 11, 1946 7 Sheets-Sheet 2 A; am;- M. SHAW INIfENTOR.

Aug. A. M. SHAW I VARIABLE CAPACITY ROTARY PUMP Filed Jan. 11, 1946 7 Sheets-Sheet 5 AL BERT M SHAW IN VEN TOR.

1952 A. M. SHAW 2,606,503

I VARIABLE CAPACITY ROTARY PUMP Filed Jan. 11, 1946 '7 Sheets-Sheet 4 ALBf/PZ' M SHAW INVENTOR.

g- 12, 1952 A. M. SHAW 2,606,503

Filed Jan. 11, 1946 '7 Sheets-Sheet 5 Aug. 12, 1952 A, SH'AW 2,606,503

VAR IABLE CAPACITY ROTARY PUMP Filed Jan. 11, 1946 7 Sheets-Sheet 6 144 BERT M Sf/flW INVENTOR.

NWT

Aug. 12, 1952 Filed Jan. 11, 1946 A. M. SHAW 2,606,503

VARIABLE CAPACITY ROTARY PUMP '7 Sheets-Sheet 7 ALBERT M SHAW INVENTOR.

byv

Patented Aug. 12, 1952 VARIABLE CAPACITY ROTARY PUMP Albert M. Shaw, Nutley, N. J assignor to Worthington Corporation, Harrison, N. J., a corporation of Delaware Application January 11, 1946, Serial No. 640,555

6 Claims. (01. 103120) This invention relates to rotary pumps, that is; positive displacement pumps embodying rotary pistons, and the primary object of the present invention is to provide means for unloading pumps of this type when conditions of operation or work performed require or render "advisable the reductionof discharge capacity of such pumps.

More specifically, the present invention embodies the rotary positive displacement pump, and means actuated by pressure differences between the suction pressure and the discharge pressure for varying the discharge capacity of the pump or completely unloading it to zero capacity.

Other objects of the present invention are to provide in a rotary positive displacement pump embodying means for automatically controlling.

its operation by varying its discharge capacity in accordance with predetermined conditions, various improvements and advantages over prior analogous pumps such as: v

The providing of constant capacity of the pump as the pressure increases from atmospheric pressure to the desired predetermined working pressure;

Variable capacity of the pump if and when the discharge pressure rises above the predetermined desired working pressure;

Unloading of the pump to zero capacity with a minimum pressure increase over the predetermined desired discharge pressure;

' Return of the pump to full capacity immediately after the discharge pressure drops to the predetermined desired degree;

,Readily and easily accomplished adjustment o f-the parts of the control mechanism to provide for proper automatic control at different desired working pressures;

Minimum heating and/ or agitation of the liquid being pumped during the unloaded operation of the pump;

Areduction in operating power consumed while the pump is operating in unloaded or reduced discharge capacity conditions;

Momentary unloading of the pump to zero capacity during starting of operation of the pump or when the pump is subjected to shock loads, together with prompt loading of the pump to capacity upon correction of such conditions, and the provision of partial adjustment of parts of the pump to compensate for wear.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing a variable capacity rotary 2 pump of a preferred form embodying the invention, and the features forming the invention will be specifically pointed out in th claims.

In the drawings:

Figure 1 is a vertical section through the rotary positive displacement pump showing the pump parts in loaded full discharge capacity operating positions; I

Figure 2 is a vertical section through the pump showing the pump parts in unloaded zero capacity operating positions;

Figure 3 is a vertical cross-section through the pump taken at right angles to the section shown in Figure 1 and taken on the line 3-3 of Figure 1;

Figure 4 is a vertical longitudinal section through a modified form of the pump;

Figure 5 is a vertical section through the modified form of the pump and taken on the line 55 of Figure 4;

Figure 6 is a fragmentary cross-section through the modified form of the pump taken on the line 66 of Figure 4 and showing the pump parts in loaded full capacity operating positions;

Figure '7 is a fragmentary vertical section through the modified form of the pump taken on the line 66 of Figure 4 and showing the pump parts in unloaded zero capacity operating positions; I

Figure 8 is a horizontal section taken on the line 8--8 of Figur 5;

Figure 9 is a vertical cross-section through a further modified form of the pump;

Figure 10 is a vertical longitudinal section through the modified form of pump shown in Figure 9 and taken on the line Ill-I0 of Figure 9.

In Figures 1 to 3 of the drawings, a positive displacement rotary pump of the type employing what is known as a sliding vane piston type is illustrated, and this form includes the casing I having a suction inlet 2 and a discharge outlet 3 with the rotor or rotating piston 4 positioned in the casing between the suction and discharge.

The rotating piston 4 comprises the carrying body 5 which is keyed upon and rotates with the drive shaft 6. A plurality of vanes l are slidably carried by the rotor 5 and project radially from the perimeter of the rotor contacting the inner surface of the bore 8' of the stator 9. During normal operation'of a pump of this type, the rotor perimeter is eccentric of the bore 8 f the stator so that the vanes l are forced inwardly from the perimeter of the rotor during its rotating operation to provide the pumping action of the fluid being pumped.

To vary the discharge capacity of the pump to a piston I8.

,reciprocatory movement in a cylinder l9, one end of which is open to the discharge passage 3. predetermined tensioned pressure is applied to shown in these figures, the relationship between the perimeter of the rotor and the inner surface of the bore 8 of the stator are varied so as to vary the degree of eccentricity between the rotor perimeter and the stator bore, thus decreasing the discharge capacity of the pump as these two elements of the pump are brought into concentric relationship so that when they are truly concentric the pump will operate at zero discharge capacity, the water being merely twirled around in the circular spac between the perimeter of the rotor and the bore of the stator.

To accomplish the adjustment or variation of the eccentric relationship of the rotor to the stator so as to vary the discharge capacity of the pump, if required, the structure shown in Figures 1 to 3 inclusive has the stator 9 rotatably carried by the casing I of the pump.

The stator Shas a transversely extending passageway [4 extending therethrough to provide communication between the suction and discharge passages 2 and 3 through the stator 9 and rotor 5. A piston rod is' pivotally connected to the perimeterof the stator'fl, as shown at [6, andis also pivotally connected, as shown at IT, The piston 18 is mounted for the end of the piston opposite that end which faces and is open to the discharge passage 3 of the pump by a spring 29. "The tension of the spring 29 may be regulated by adjustment of nut 2 l.

A passage 22 opens into the cylinder 9 at'the outerendof 'the'piston If}, that is, on the side of the piston opposite to that side which is subjected or open to discharge pressure from the dischargepassage 3. The passage 22 has commiinioation through a valve chamber 23 and a passage 24 'with the suction passage 2 of the pump. 7 A piston valve '25 is mounted for reciprocatory movement in the valve chamber 23 and to control the flow of liquid pumpedthrough the passage 22 from the cylinder l9. One end of the valve chamber 23 is open to discharge pressure of the pump as shown at 26 so thatone end of the valve is subjected to discharge pressure, while the other 'endof the valve is subjected to suction pressure ,by means of the passage 24 anda passage .28 formed in the housing of the valve chamber 23. The end of the valve 25 which is subjected'to suction pressure is also subjected to regulated tension pressure by means of a spring29 which engages the end of the valve 25 opposite to that subjected to discharge pressure. 'Thextension ofthe spring 29 is regulated by an adjusting tension nut 30.

The piston. I 8 has a pressure equalizing port 3| extending therethrough, thepurpose of which will be broughtjout in thefollowing description of the operation of the pump capacity varying or regulating means.

the I During normal operation of the pump, when the discharge pressure of the' pump is at orbelow a predetermined desired discharge pressure for the work tobe performed, the combined pressure of the suction pressure fluid'and'the spring'29 will be sufficient to holdthe piston valve 25 in closed position (as shown in Figure 1 of the drawings) against the action of the discharge pressure of the pump; and atsuch time, the piston [8 will be in its lowermost position, being held therein by the pressure of the spring 20 and the pressure of liquid or fluid which leaks into the cylinder [9 through the pressure equalizing port 3!. At this time, the stator 9 will be held in the position shown in Figure l of the drawings, that is, with a maximum degree of eccentric relationship between the bore 8 of the stator and the perimeter of the rotor 4. At this time the pump will operate at full discharge capacity.

In the event the discharge pressure builds up beyond the desired discharge pressure for the work to be performed, such increased discharge pressure will act upon the valve 25 and move the valve upward against the combined pressure of the spring 29 and of the suction fluid acting upon the valve. This opening movement of the piston valve 25 will permit fluid to flow through the port 22 from the cylinder Hi to the pump suction at a greater rate than the discharge pressure fluid can flow through the equalizing opening or port 3!, and thus the pressure on opposite sides of the piston l8 will become unbalanced, causing the discharge fluid or liquid at the higher pressure to force the piston 13 upwardly and rotate the stator 9. It will be appreciated that any degree of pressure rise-less than the pressure difierence required to cause maximum movement of the piston 8 will result in'partial movement of the piston 8 with partial rotation of the stator 9 between the-amount of rotation required to move the stator so that the perimeter of its bore 8 and the perimeter of the rotor 4 will be in true concentric relation. but when these members are in true concentric relation the pump will be operating at zero capacity. Thus it will be seen that through the effects of the pressure difference between the suction pressure of fluid entering the pump and the discharge pressure'of fluid leaving the pump, above a predetermined degree controlled by the adjustment of the tensions of the springs 29 and 29, the discharge capacity of the pump will be regulated in increments corresponding to this pressure difference and thus the pump will automatically be adjusted to operate at various percentages of its full discharge capacity from full load or capacity to zero capacity or unloaded con dition.

As the discharge pressure of thepump reduces, due to reduced discharge capacity and load conditions, the spring 29 will move the valve 25 to cut off communication between the passage 24 and the cylinder I!) and the pressure above the piston l8 will quickly become equal to the discharge pressure of the pump through the bleeding of discharge pressure fluid through the pressure equalizer port or opening 3 I. When the fluid pressure on the opposite sides of the piston 18 is equalized, the spring 29 will force the piston l8 downwardly, and, consequently, movethe connecting arm or rod l5 and the stator back to the normal position shown in Figure 1 of the drawings, and the pump will discharge at its-full discharge capacity. The degree of speed'of return of the stator to its normal full capacity operating position may be regulated by regulating the size of the bleeder port or opening 3|. Thus by reducing the size of this port to a certain camerciallyknown as a rotary gear pump embodying herringbone gears which form the rotative positive displacement piston of the pump.

This form of pump includes a casing 40 having a suction inlet 4| and a discharge outlet 42 between which are'positioned a pair of normally intermeshing herringbone gears 43 and 44. The driving gear 43 is mounted on a shaft 45 which is rotated by any suitable type of prime mover (not shown) and during full capacity operation of the pump it meshes with the driven gear 44 to provide the pumping action of the pump.

In the form shown in the drawings, the driven gear 44 is mounted upon a stub shaft 46 which is in turn supported by a suitable bearing collar 48 rotatable in a recess 49 in the housing 40. The

bearing collar 48 has a crank thereon in the form of an eccentrically mounteddisc 50 (see Figures 4 and 5 of the drawings) so that rotation of the eccentric 50 will vary the distance between the axes of the driving shaft 45 and the driven stub shaft 46, and, consequently, vary the distance between the axes of the driving herringbone gear 43 and the driven herringbone gear 44, resulting in a variation of the degree of surface meshing of the teeth of the two gears, and, consequently, varythe discharge capacity of the pump. Figure 6 shows the gears in full tooth surface meshing arrangement at which time the pump will operate at full discharge capacity, while Figure '7 of'the drawings shows them in partial surface meshing engagement, namely, of such a degree as to-result in zero discharge capacity operation of the'pump. The portionof the casing 40 in which the driven gear 44 rotates has its bore 51 shaped so as to accommodate the movement of the driven gear 44 relative .to the driving gear 43 for the varying of the capacity of the pump. 3 The crank or eccentric 50 is connected by a ,connecting rod 52-to a piston 53. The piston 53 is mounted for reciprocatory movement in a cylinder 54, one end of which is open to discharge pressure in the pump, while the other end is open to suction pressure of the pump through a passage 55 when the valve 56 is open. The valve 56 and the piston 53 are identical, both in structure and operation, with the piston 18 and valve 25 described in connection with the form of the invention shown in Figures 1 to 3 of thedrawings,

pressure of the pump rises above a predetermined degree regulated by the tension of the spring 51 which corresponds to the spring 29, the valve 56 will be opened by the action of discharge fluid pressure of the pump, thus causing a pressure difference on opposite sides of the piston 53 so that the piston53 will be moved by discharge pressure to rotate the crank or eccentric 50 and move the driven gear 44 to vary the relationship between the driving and driven gears of the pump to vary the discharge capacity of the pump from full load capacity to zero load capacity in accordance with the pressure difference between the suction pressure and the discharge pressure of the pump.

Figures 9 and of the drawings show a still further modification of a positive displacement rotary pump of variable capacity. The pump shown in Figures 9 and 10 is of the spur or single helical gear rotary pump in contradi'stinction' to the herringbone or double helical gear type shown in Figures 4 to 8 inclusive.

In the pump structure shown in Figures 9 and 10, of the drawings, a pair of spur or single helical gears 65 and 61 comprise the rotary piston of the pump. The-spur gear 60 is mounteduponthe drawings, and it has a liner 68 attached theretowhich is contacted by the periphery of the teeth of the driven spur gear 6|. The bearing block 61 is movable'longitudinally of the axis of the spur gear 6| so as to move the spur gear 6 l longitudinally relative to the driving spur gear 63 to vary the degree of surface meshing contact between the driving and driven spur gear to vary the discharge capacity of the pump. A spring 69 engages the casing 53 and the slidable bearing block 61 and is tensioned so that it, together with the pressure of discharge fluid which leaks through the pressure equalizing ports H1 into the chamber ll, will counterbalance the normal desired discharge pressure of the pump in the chamber 12 all; the opposite end of the slidable bearing block A valve chamber 14 is formed in the casing 63, and it has one'end open to the discharge passage 65 of the pump as shown at 15. A sliding piston valve 76 is mounted in the valve chamber 64 and it controls the flow of discharge pressure from the discharge outlet 65 of the pump through the passage 71 into the chamber 72, that is, against the end of the bearing block 6'! opposite to that against which the spring 69 engages. A passage 18 admits suction pressure fluid to the valve chamber 14 against the end of the valve opposite to the end which is subjected to discharge pressure of the pump, and this suction pressure together with the tensioned pressure applied against the sliding valve 16 by the spring 19 holds the valve 16 in closed position until such time as the discharge pressure in the pump exceeds the combined suction pressure and the tensioned pressure of the spring 19; that is, until the discharge pressure exceeds the desired operating pressure. When this occurs, the valve 16 is moved to open the passageway" and permit discharge fluid to flow into the chamber 12 and move the sliding block 61 in proportion to the pressure difference between the pressures on the opposite ends of the bearing block so as to shift the driven spur gear BI and vary the discharge capacity of the pump. The movement of the spur gear 6! against the action of the pressure fluid in the chamber H causes a reduction in the length of tooth contact of the spur gear 60 and GI, with a resultant reductionof liquid displacement. As soon as the discharge pressure drops to the desired point, or below the combined suction pressure and tension pressure of the spring 19, the spring 19 will close the pilot or distributing valve 15, and the pressure on each end of the slidable bearing block 6'! will equalize or balance through the pressure equalizing holes Ill, and the spring 69 will return the bearingblock and the spur gear 6| to their original normal positions, as shown in Figure 10 of the drawings, and full discharge capacity of the pump will be re-established.

It will be understood that the invention is not to be limited to the specific construction or arwidely modified within the invention defined by the claims.

What is claimed is:

1. In a positive displacement rotary pump, means for varying the discharge capacity of the pump including a cylinder, a piston in said cylinder, tensioned pressure applying means in said cylinder and applying tensioned pressure against one-end of said piston, the other end of said piston being subjected to discharge pressure of the pump,said piston provided with a pressure equalizing port extending therethrough to allow bleeding of discharge pressure fluid into the cylinder against the end of the piston subjected to the tensioned pressure, and-means operated upon a rise in the pressurediiference between thesuction and discharge pressures beyond a predetermined degree toovercome the pressure equalization on opposite ends of the piston to allow movement of the piston by discharge pressure fluid, and means operated by movement of the piston to vary-the discharge capacity of the pump.

2. In a positive displacement rotary pump, means'for varying the discharge capacity of the pump including a cylinder, a piston in said cylinder, tensioned pressure applying means in said cylinder and applying tension pressure against one end of the piston, the other end of the piston being subjected to discharge pressure of the pump, said piston provided with a pressure equalizing port extending therethrough to allowbleeding of discharge pressure fluid into the cylinder against the end of the piston subjected to said tensioned pressure, a distributing valve, means whereby said distributing valve will be operated upon a risein the pressure difference between the suction and discharge pressures of the pump beyond a predetermined degree to permit flow of fluid from said cylinder to overcome the pressure equalization on the opposite ends of the piston to allow movement of the piston, and means operated by movement of the piston to vary the discharge capacity of the pump.

3. In a positive displacement rotary pump including a casing, a driving rotary piston and a driven rotary piston cooperating therewith, of

,means for varying the discharge capacity of'the pump including a cylinder, a piston in said cylinder, tensioned pressure applying means in said cylinder andapplying tensioned pressure against one end of saidpiston, the other end of said pistonbeing subjected to discharge pressure of the pump, said piston provided with -a pressure equalizing port extending therethrough'to allow bleeding of discharge pressure'fluid into the cylinder against the end of the piston subjected to saidtensioned pressure, means operated upon a rise in the pressure difference between the suction and discharge pressures of the pump beyond a predetermined degree to overcome the pressure equalization on the opposite endsof the piston for allowing movement of the piston by discharge pressure fluid, and means operated by movement of the piston to vary the discharge capacity of the pump.

.4. A positive displacement pump as claimed in claim 1 wherein said piston operated means for varying the discharge capacity of thepump comprises, an eccentric, a piston rod pivotally connected to said eccentric and to said piston'for rotating the eccentric by movement of the piston to vary the discharge capacity of the pump,:and adjustable means acting upon said.pressure difference actuated means whereby said pressure difierenceactuated means may be regulated to be operated by various predetermined pressure differences between the suction and discharge pressures of the pump.

5. In a positive displacement rotary pump embodying a casing provided withan inlet and out- .let passage, a stator mounted for limited rotary movement in said casing, said stator provided with a cylindrical bore arranged eccentrically of the axis of rotation of the stator, a rotary piston in said eccentric cylindrical bore, sliding vanes carried by said rotary piston and engaging the wall of said eccentric cylindrical bore, means for Varying the discharge capacity of the pump by varying the degree of eccentricity betweenthe perimeter of the rotary piston and the eccentric cylindrical bore of the stator, a cylinder carried by said pump casing-and having communication with the'inlet and outlet of the pump, a reciprocatory piston in said cylinder and subject to discharge pressureonits outer end, means for equalizing the pressure against both ends of said piston, :a valve controlling communication of said cylinder with the inlet of said pump, means holding said valve closed during normal operation of the pump and to allow opening of the valve when the pressure difierence between the suction and dischargepressures of the pump rise above a predetermined amount, the opening of said valve acting to open the cylinder to the pump suction to break down the equalized pressure on the opposite ends of said piston whereby said piston will be moved by discharge pressure of the pump when said valve is opened, and means connecting said piston andsaid stator to rotate the stator relative to the rotor upon movement of the piston to vary the discharge capacity of the pump.

6.'In' a positive displacement rotary pump embodying a casing iprovidedwith an inlet andoutlet passage, a stator mounted for limited rotary movement in saidcasing, said stator provided with a cylindrical borea-rranged eccentrically of the axis of rotation of the stator, a rotary piston in said eccentric cylindrical bore, sliding vanes carried by said rotary piston and engaging the wall of said eccentric cylindrical bore,'means for varying the discharge; capacity of the pump'by varying the degree of eccentricity between the perimeter of the rotary piston and the eccentric cylindrical bore of thestatona cylinder carried by said pump casing and having communication with the inlet'and outlet of the pump, a reciprocatory1 piston in said cylinder and subject to discharge pressure onits outer end, means for equalizingthe pressure against both ends oflsaid piston, a valve controlling communication of said cylinder with the inlet of said pump, means holding said valve closed during normal operation of the pump and to allow opening of the valve when the pressure difference between-the suction and discharge pressures of the pump rise above a predetermined amount, the opening of said valve means may be regulated to be operated by various predetermined degrees ofv pressure difierence betweenthe suction and, discharge pressures of the pump, tensioned means for applying tensioned pressure against said valve, and adjustable means for regulating the tension of said tensioned applying means.

ALBERT M. SHAW.

REFERENCES CITED The following references are of record in the file of this patent:

Number 15 Number 10 Name Date Wilkin Mar. 7, 1939 Clark July 18, 1939 Johnson Mar. 5, 1940 Kendrick Apr. 15, 1941 Kendrick Apr. 15, 1941 Kendrick Sept. 16, 1941 MacNeil Nov. 11, 1941 Ernst Feb. 29, 1944 Egersdorfer Aug. 14, 1945 Dillon Aug. 26, 1947 Clarke Dec. 6, 1949 FOREIGN PATENTS Country Date Great Britain Sept. 29, 1932 Great Britain Dec. 8, 1932 Great Britain Aug. 5, 1938 Great Britain Nov. 11, 1940 Great Britain Jan. 2, 1946 Germany May 4, 1933 France Jan. 24, 1938 

